The morphological diversification of pollinia of some members of Asclepiadaceae

Abstract

Most of the natural systems of plant classification have been based on exomorphic characters. The flower is a primary reproductive character considered to be more important than any vegetative characters. The mass of pollen grains is basically called pollinia. Like pollen, the pollinium is also the key character for the identification of specific plant species belonging to the family Asclepiadaceae (Dicotyledons) and Orchidaceae (Monocotyledons). Pollinial characters are now being used as important taxonomical tool for reassessing the different types of plant groups. The morphological nature of pollinia is specific in each genus. The morphological diversifications of pollinium of different genera of Asclepiadaceae were studied with the help of light microscope and phase contrast microscope (Leica-DM1000). The shape, size, position, orientation of pollinia, translator attachment, furrow position, etc are important criterion for the studies of pollinial morphology. This study analyzed the pollinial morphology of some selected plant taxa like Calotropis gigantea (L.) Ait., Daemia extensa R.Br., Dregea volubilis Benth, Gymnema sylvestre R.Br, Hoya globulosa Hook.f. and Tylophora indica (Burm.f.) Merr. collected from different parts of West Bengal.

Key words: Asclepiadaceae, Orchidaceae, morphology, pollinia.